PROJECT SUMMARY This application requests funds to refine and rigorously test a collaborative care model for patients with opioid use disorder (OUD) and major depression, post-traumatic stress disorder, or an anxiety disorder in primary care. We also will examine clinician and practice characteristics associated with successful implementation and the cost effectiveness of different care models. The primary aims of this proposal are: (1) Rapidly prototype and test each element of our collaborative care models to optimize it for implementation; (2) Conduct a randomized study of three collaborative care conditions with 39 practices to determine which is most effective in improving outcomes for people with OUD and mental health conditions: (a) Augmented Usual Care: PCP waivered to prescribe buprenorphine and mental health care manager, (b) Collaborative Care: Waiver PCP; mental health care manager receives OUD training; practice receives telephonic psychiatric consultation, or (c) Collaborative Care + Social Worker to address social determinants of health; (3) Measure clinician and organizational-level factors associated with implementation of each component, with the goal of developing strategies to increase successful implementation; (4) Conduct a cost evaluation of each collaborative care model; and (5) Work with smaller and more rural practices to develop and test effective strategies to manage OUD. Successful completion of the proposed study will provide definitive evidence regarding the most parsimonious set of elements of integrated collaborative care required to maximize outcomes for individuals with OUD and psychiatric disorders. Because of the study design, our examination of implementation factors, and our community partnerships, the results also will have high probability of adoption and implementation.